This invention relates to the construction of a windshield wiper for a vehicle, for example, and more particularly it is concerned with a device for avoiding vibration of a wiper blade attached to the forward end of a wiper arm caused by frictional dragging on the windshield.
In recent years there has been a marked increase in the speed at which vehicles, particularly automotive vehicles, travel. One of the problems that have been raised by the increased vehicle speed is that the blade of the windshield wiper is separated from the windshield by the pressure of the air during high speed travel of the vehicle. To solve this problem, proposals have been made to increase the force with which the windshield wiper blade is forced against the windshield. A resilient member formed as of rubber is usually attached to the wiper blade and maintained in contact with the windshield for cleaning same. With an increase in the force with which the wiper blade is forced against the windshield, stick slip would occur when the wiper blade moves in sliding movement on the windshield because the coefficient of friction between the resilient member and the surface of the windshield may vary depending on the difference between the relative speeds thereof. This phenomenon would tend to occur when the surface of the windshield is wet. This phenomenon which is caused by the difference in rigidity between the wiper arm, wiper blade and the wiper driving link and the manner in which they are fastened together would cause the wiper blade to vibrate at a frequency of 5-20 Hertz. This vibration is generally referred to as a chattering vibration and causes unpleasant sounds to be produced or water drops to be left unwiped on the windshield.
It would be possible to avoid this phenomenon by increasing the rigidity of various parts to a satisfactory level and fastening them together to avoid their wobbling. However, when such factors as an increase in the size of various components tending to interfere with the visibility of the driver, an increase in the load of the wiper motor and an increase in cost are taken into consideration, the aforesaid means for avoiding the fretting of the windshield wiper would not be considered particularly advantageous.